Sam Raimi, who was supposed to direct the WoW movie before Duncan Jones got it recently, has talked about the process he went through with Blizzard in an interview with Vulture. Here's the relevant quote about the mismanagement on Blizzard's side:
Robert Rodat was working on the script, and it was taking a long time. I think they were getting a little antsy at Legendary, the production company. Actually, what happened was even more complicated, so let me go back a little bit. First, they asked me if I wanted to make it, and I said, "Yes, I love World of Warcraft, and I think it would make a great picture." So I read a screenplay they had that was written by the guys at [Warcraft developer] Blizzard, and it didn't quite work for me. I told them I wanted to make my own original story with Robert, so we pitched it to Legendary and they accepted it, and then we pitched it to Blizzard, and they had reservations, but they accepted it. Then Robert wrote the screenplay, and only once he was done did we realize that Blizzard had veto power, and we didn't know that. And they had never quite approved the original story we pitched them. Those reservations were their way of saying, "We don't approve this story, and we want to go a different way," so after we had spent nine months working on this thing, we basically had to start over. And Robert did start over, but it was taking too long for the people at Blizzard, and their patience ran out. Honestly, I think it was mismanagement on their behalf, not to explain to us that the first story was vetoed long ago. Why did they let us keep working on it? Were they afraid to tell me?
And, about the new director:
I loved his movie Moon, and I think he's a strikingly talented director. I bet that if anyone can do a great job with it, it's him.
To be honest, I think the movie is in much better hands now as Jones seems a much more talented director and a "real gamer" as he describes himself. Now the real question is, considering Blizzard's recent track record on stories (DIablo 3, Starcraft 2), was the script they vetoed actually really good and instead we might get something more along the lines of "throw Diablo and his soulstone off the edge, I'm sure he won't come back like he did 1231 times so far"?
Rob Pardo refered via Twitter to the Interview: "I don't want to create controversy, but there are two sides to every story[...]"
Here's an old (and pretty good) casting pick from around the net: